What are Mendel’s Laws in terms of heredity?
Mendel’s laws of inheritance are based on his observations on monohybrid crosses.
He proposed the following laws of inheritance:
1. Law of Dominance (First Law):
The law of dominance states that when two alternative forms of a trait or character (genes) are present in an organism, only one factor expresses itself in F1-progeny and is called dominant, while the other that remains masked is called recessive.
This law is used to explain the expression of only one of the parental characters in a monohybrid cross in the F1 -generation and the expression of both in the F2-generation. It also explains the proportion of 3:1 obtained in theF2-generation.
2. Law of Segregation (Second Law):
This law states that the alleles do not show any blending and both the characters are recovered as such in the F2-generation, though one of these is not seen in the F1 -generation.
Due to this, the gametes are pure for a character. The parents contain two alleles during gamete formation.
The factors or alleles of a pair segregate from each other such that a gamete receives only one of the two factors.
3. Law of Independent Assortment (Third Law):
This law states that when two pairs of traits are combined in a hybrid, segregation of one pair of character is independent of the other pair of characters at the time of gamete formation.
It also get randomly rearranged in the offsprings producing both parental and new combinations of characters. The law was proposed by Mendel, based on the results of dihybrid crosses, where inheritance of two traits were considered simultaneously.